Multi-loop temperature control system for a semiconductor manufacture process

ABSTRACT

A temperature control system for a semiconductor manufacturing process having at least one target includes: a heat exchange loop operatively associated with each target, and a mixing valve operatively associated with each heat exchange loop. This mixing valve has a body defining a mixing chamber. The mixing chamber has an inlet, an outlet, a hot inlet, a cold inlet, and a closure means associated with each inlet. Alternatively, the mixing valve may include: a body defining a mixing chamber, the mixing chamber having an inlet, an outlet, a hot inlet, and a cold inlet, a moveable gate operatively associated with each inlet for controlling the flow of fluid through said inlets, and a motor for moving the gates. A process for manufacturing semiconductors includes the step of providing a temperature control system having at least one target including a mixing valve, as described above.

FIELD OF THE INVENTION

The instant invention is directed to a multi-loop temperature control system for a semiconductor manufacture process, a control valve used therein, and a process for manufacturing semiconductors.

BACKGROUND OF THE INVENTION

The need for specialized thermal control systems for use in the manufacture of semiconductor devices is known. For example, see U.S. Pat. Nos. 6,026,896, 7,069,984, 7,225,864, 6,822,202, 7,180,036, 7,870,751, and 8,410,393, each of which is incorporated in its entirety herein.

U.S. Pat. No. 6,026,896 teaches a heat exchanger, a manifold coupled to the heat exchanger, a plurality of fluid passages coupled to the manifold, a flow control valve in each fluid passage, and a process component associated with each fluid passage, FIG. 1. The controller may control the temperature of a device with multiple process components, FIG. 2. The controller may have two manifolds for distributing heat transfer fluid at differing temperatures, FIG. 3. The valve 74 is a 3-way valve for mixing the heat transfer fluids of the differing temperatures.

U.S. Pat. No. 7,069,984 & U.S. Pat. No. 7,225,864 teach a remote temperature control module (RTCM) for use in a temperature control system for a semiconductor process component. The RCTM includes a loop to the source of cooling fluid, a loop to the process component (tool), a heat exchanger thermally connecting the loops, and may include a heat source (362). The cooling loop includes a control valve coupled to a temperature controller.

U.S. Pat. No. 6,822,202 & U.S. Pat. No. 7,180,036 teach a temperature control system for use in a semiconductor process component. This system includes a loop to the process component, a loop to a first source of fluid, and a loop to a second source of fluid. The first and second fluid sources are at different temperatures. The first and second fluids are used, by mixing with the fluid of the process component loop, to control the temperature at the process component.

U.S. Pat. No. 7,870,751 teaches a temperature control system for use in a semiconductor process component. This system includes a first loop to multiple processing components arranged in parallel (FIGS. 2 & 5), a second loop coupled to a chiller, a heat exchanger thermally connecting the first and second loops, a control valve and heater on each line from the first loop to the process component.

U.S. Pat. No. 8,410,393 teaches a temperature control system for use in a semiconductor process component. This system utilizes, for example see FIG. 5A, a set of recirculators, 510/520/530/540, each at a different temperature, and switching valves 561/562, to circulate fluid to the process component to control the temperature at the process component.

While each of the foregoing devices has served well, there is a continuing need for the improvement for these specialized semiconductor manufacturing temperature control devices. Heretofore, semiconductor processes where conducted one step at a time. For example, one etch or material deposition step was performed on a wafer, and then the wafer was moved to the next step. Or, only one layer of the wafer was worked in a given step. Now, however, there is a need to increase throughput in these manufacturing processes. As progress is made to increase the size of the wafers, for example to 450 mm or more, there will be increased efforts to perform multi-step etchings and depositions, as well as, multi-layer etchings and depositions that are performed without movement of the wafer (which increasing the chance of, for example, particle contamination). These multi-step and multi-layer processes will require, among other things, more demanding temperature control because the etch/deposition rate, resolution (selectivity), and etch/deposition control for each step must be tailored to the process involved. Each of these considerations will require, for example, attention to fine temperature control to facilitate the process step, quick temperature set point movement from step-to-step, and varying power consumption (heating/cooling demand) for each step. Accordingly, there is a need for a new temperature control system for use in the semiconductor manufacturing process.

SUMMARY OF THE INVENTION

A temperature control system for a semiconductor manufacturing process having at least one target includes: a heat exchange loop operatively associated with each target, and a mixing valve operatively associated with each heat exchange loop. This mixing valve has a body defining a mixing chamber. The mixing chamber has an inlet, an outlet, a hot inlet, a cold inlet. A closure means is associated with each inlet. Alternatively, the mixing valve may include: a body defining a mixing chamber, the mixing chamber having an inlet, an outlet, a hot inlet, and a cold inlet, a moveable gate operatively associated with each inlet for controlling the flow of fluid through said inlets, and a motor for moving the gates. A process for manufacturing semiconductors includes the step of providing a temperature control system having at least one target including a mixing valve operatively associated with each target, the mixing valve having a body defining a mixing chamber, the mixing chamber having an inlet, an outlet, a hot inlet, a cold inlet, and a closure means associated with each inlet.

DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in the drawings a form that is presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIG. 1 is a schematic illustration of the inventive temperature control system (only two targets shown).

FIG. 2 is a schematic illustration of the inventive mixing valve.

FIG. 3 is a schematic illustration of the inventive mixing valve with the gates moved to a position.

FIG. 4 is a schematic illustration of the inventive mixing valve with the gates moved to another position.

FIG. 5 is a schematic illustration of the inventive mixing valve with the gates moved to yet another position.

FIGS. 6 a-d are schematic illustrations of a gate of the inventive mixing valve.

FIG. 7 is an illustration of heat flow, mass flow, and temperatures for an embodiment of the invention.

FIGS. 8 a-c are illustrations of inventive temperature control system in operation with a representative sample of the programming logic of the controller.

DESCRIPTION OF THE INVENTION

Referring to the figures, where like element have like numerals, there is shown in FIG. 1 the temperature control system 10. System 10, all or parts thereof, may be contained within the clean room 12. A source of cold fluid A and a source of hot fluid B may be located outside of the clean room 12.

For the purpose of illustration, FIG. 1 shows system 10 controlling the temperature of two targets 14, 14′. It being understood, that the system 10 is not so limited; instead, the system 10 may control the temperature of a single target or multiple targets (i.e., >2, e.g., 2, 3, 4, 5, 6 . . . ). The maximum number of targets being limited only by the size of the clean room 12 and the capacity of the cold fluid source A and the hot fluid source B. The systems 10 may be controlling the temperature of the their respective targets 14 to the same temperatures profiles as other targets or to different profiles. For example, each system 10 may be programmed for the same temperature profile or each system 10 may be programmed with different temperature profiles.

Target, as used herein, refers to semiconductor processing equipment or semiconductor processing techniques/steps used to convert the virgin wafer into a semiconductor device(s) or semi-work semiconductor. These targets include any process by which the wafer is converted to a semiconductor(s) or semi-work semiconductor(s). Such process are well known and include, for example: deposition processes—chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), cupper deposition, sputter deposition; etching—dry etching, plasma etching, electron beam evaporation; resist strip, to name a few. The system described, hereinafter, may have particular relevance to etching processes, and/or those processes conducted in vacuum chambers. In operation, the wafer within the target and is thermal communication with the system 10. As the various processes are used to convert the wafer in the semiconductor, the system 10 may be used to control the temperature (as well as the removal or input of heat into the wafer) as may be required to facilitate the completion of the process.

In general, system 10 is coupled to a cold loop 18 and a hot loop 24. The terms cold and hot are relative terms and are used to indicate differing temperatures. The exact temperature of cold and hot will be dictated by the requirements of the processes discussed above. It is desirable that the temperature difference between the hot and cold loops be as great as possible. These larger temperature differences facilitate quick change of the set point at the target. As an example, the system may have: a cold loop temperature (T_(a)) of −20° C. and a hot loop temperature (T_(h)) of 150° C.; or a T_(c) of 0° C. and a T_(h) of 120° C.; or a T_(c) of 10° C. and a T_(h) of 100° C. (or any combination or subcombination therebetween of the temperatures in those ranges). Coupling may be in any fashion, but typically refers to a parallel coupling, as opposed to a series coupling. Cold loop 18 includes a cold loop feed 20 and a cold loop return 22. Additionally, the cold loop 18 may include a cold loop temperature sensor 19, for example in feed 20. Hot loop 24 includes a hot loop feed 26 and a hot loop return 28. Additionally, the hot loop 24 may include a hot loop temperature sensor 25, for example in feed 25. There may be more than one temperature sensor in the respective loops. The temperature sensors are operatively connected to a controller 50.

System 10, referring generally to the left hand side of FIG. 1, may include target 14, a recirculating pump 32, and a mixing valve 100, discussed in greater detail below. Additionally, system 10 may also include a pump supply tank 38, a flow sensor 34, and a temperature sensor 36 (the sensors are operationally connected to the controller 50). The target may include a temperature sensor (not shown) that is operationally connected to the controller 50. A heat exchange fluid may be any heat exchange fluid. Exemplary heat exchange fluids include FLUORINERT or GALDEN. The heat exchange fluid may be circulated between the mixing valve 100 and the target 14. The supply tank 38 and the expansion tank 40 are intended to act as a reservoir for excess fluid that may arise by action of the mixing valve 100.

Mixing valve 100, discussed in greater detail below, has a process inlet 102, a process outlet 104, a cold inlet 106, and a hot inlet 108. The cold loop 18 is in thermal communication with the cold inlet 106 of valve 100. Heat exchange fluid is drawn from the cold loop feed 20 through a flow sensor 42, operatively connected with controller 50, to one side of a heat exchanger 44 and returned to cold loop return 22. The cold inlet 106 is in fluid communication with another side of the heat exchanger 44. The hot loop 24 is in thermal communication with the hot inlet 108 of valve 100. Heat exchange fluid is drawn from the hot loop feed 26 through a flow sensor 46, operatively connected with controller 50, to one side of a heat exchanger 46 and returned to hot loop return 28. The hot inlet 108 is in fluid communication with another side of the heat exchanger 46.

System 10′, referring generally to the right hand side of FIG. 1, is identical to system 10. Moreover, systems 10 may be expanded, as discussed above.

In operation, the heat exchange fluid is in thermal communication with the wafer held within the target 14, for example, by a wafer chuck (not shown) of the target 14, and is pumped to the mixing valve 100 by means of the pump 32. In a steady state mode, the fluid is circulated through valve 100, 100% in and 100% out via process inlet 102 and process outlet 104. However, when the temperature set point needs to be changed (increased or decreased as may be demanded by the process being conducted at the target 14), the mixing valve comes into active operation. The mixing valve 100 selectively mixes, as will be discussed below, cold or hot fluid via cold inlet 106 or hot inlet 108, while reducing flow at inlet 102, and thereby changes the temperature of the fluid exiting outlet 104. All of these being controlled by controller 50 which receives input from the noted flow and temperature and outputs instruction to the mixing valve 100.

The mixing valve 100 is shown in greater detail in FIGS. 2-5.

In FIG. 2, mixing valve 100 is shown in greater detail. Valve 100 generally includes, for example, a body 110 and a motor 118. The body 110 defines a mixing chamber 112. The process inlet 102 empties into the chamber 112 and the process outlet 104 exits from the chamber 112. Additionally, the cold inlet 106 and the hot inlet 108 empty into chamber 112. Gates 114 and 116 are moveably mounted on the body 110 within the chamber 112. As illustrated, compare FIGS. 2-5, the gates may be slidably mounted on the housing. The gates 114/116 are used to open and close the inlets 102/106/108, as will be explained in greater detail below, and thereby allow heat exchange fluids of various temperatures to mix in chamber 112 prior to exit via outlet 106. The gates 114/116 are operatively coupled to the motor 118 via an actuator 120.

In FIGS. 6 a-d, a front elevational view of one gate 114 is shown (gate 116 may be a mirror image of gate 114). Gate 114 has a gate portion 150 and a lug portion 160. The lug portion 160 includes an actuator connection 162. The gate portion 150 has a leading edge 152 and a trailing edge 154. Leading edge 152 is the edge that engages the process inlet 102. The trailing edge 154 engages the cold inlet 106 or hot inlet 108, as the case may be. The leading edge 152 and the trailing edge 158 may include a profile 156 and 158, respectfully. The profiles 156/158 may include any profile. The profiles 156 and 158 may be mirror images. In FIG. 2, the gate has a flat profile. In FIG. 6 a, the profiles 156/158 include a triangular (or diamond) protrusion. In FIG. 6 b, the profiles 156/158 are inclined flat protrusion. In FIG. 6 c, the profiles 156/158 are arcuate protrusion. In FIG. 6 d, the profiles 156/158 are trapezoidal protrusion. The profile may include multiple protrusions and multiple and varying protrusions. While not being bound by any theory, it is believed that the profiles 156/158 may contribute to the control of the temperature of the target and/or enhance the sensitivity of the temperature control.

The body 110, see FIG. 2, may be made of several pieces 110 a/110 b/110 c to facilitate assembly. If manufactured in this way, seals 128/130/132/134, for example O-rings, may be used to prevent leakage between these pieces.

Motor 118, see FIG. 2, may also be coupled to body 110 and seal 124 may be used to prevent leakage between the motor 118 and body 110. Motor 118 may also include a bearing 126. Bearing 126 may be a sealing bearing to prevent leakage.

Motor 118 may be any motor capable of moving gates 114/116. Motor 118′s operation is controlled via a connection to controller 50. Motor 118 is operatively connected to gates 114/116 via an actuator 120. Actuator 120 may be mounted in body 110 via a bearing 122. As shown, motor 118 is a stepping motor that rotates actuator, e.g., a threaded rod. The gates 114/116 are mounted on actuator 120, so that as actuator rotates, the gates 114/116 open and close inlets 102/106/108. While motor 118 is shown as a stepper motor, it is not so limited and other mechanisms may be used to move gates 114/116. Such mechanisms include, without limit, servomotors, linear motors, and hydraulic motors.

Gates 114/116 are configured in such a way that by action of the actuator 120, they open and close the inlets 102/106/108. This is best illustrated by comparison of FIGS. 2-5. In FIG. 2, the gate position is such that fluid passes through the valve, 100% in, inlet 102, and 100% out, outlet 104. This position represents normal operation, i.e., steady state temperature at the target. However, if the set temperature must change, for whatever reason, the controller sends a signal to the motor 118. That signal is translated in movement of the gates 114/116.

In FIGS. 2-5, several gates positions are illustrated, it being understood that many variations are possible. In FIG. 3, hot inlet 108 is partially opened, process inlet 102 is partially closed, and cold inlet 106 is completely closed. In this configuration, hot fluid is mixed with fluid in the process loop, so that the temperature of the process loop fluid is increased. In FIG. 4, cold inlet 106 is fully open, and hot inlet 108 and process inlet 102 are completely closed. In this configuration, cold fluid replaces with fluid in the process loop, so that the temperature of the process loop fluid is decreased. In FIG. 5, cold inlet 106 and process inlet 102 are partially and hot inlet 108 is closed. In this configuration, cold fluid is mixed with fluid in the process loop, so that the temperature of the process loop fluid is decreased.

As will be apparent to those of ordinary skill, the temperature and volume (or mass) of the cold/hot fluid will control the time it will take to decrease/increase the temperature of the fluid circulating in the process loop to the target 14. It should be noted, that as gates 114/116 open/close cold/hot inlets 106/108, the gates 114/116 close the inlet 102, so that a material balance (inflow=outflow) is maintained around the mixing chamber. To more fully illustrate this point, the following non-limiting example is provided, it being understood that there may be other methods for determining the necessary parameters. FIG. 7 illustrates an embodiment of the invention where hot inlet 108 is closed and cold inlet 106 and process inlet 102 are partially open. Energy Q₁ is inputted into target 14. Heat exchange fluid pumped to target 14 enters at T₁ and exits at T₂ (those of ordinary skill will recognize that T₁ is <T₂ when Q₁ is positive). To maintain the target 14 at a constant temperature, Q₁=Q₂. To determine T₁, T₁=(M_(c)T_(c)+M_(p)T₂)/(M_(l)+M_(p)), where: T₁ is the temperature into the target, M_(c) is the mass flow cold, T_(c) is the temperature cold, M_(p) is the mass flow process, and T₂ is the temperature process.

In FIGS. 8 a-c, a process for manufacturing a semiconductor using the foregoing temperature control system 10 is illustrated.

FIG. 8 a is a graph of the temperature profile at the target 14. The x-axis is time (t_(x), x=0, 1, 2, 3 . . . n, & t′_(x), x=0, 1, 2, 3 . . . n). The y-axis is temperature (the temperatures are for illustration only and may be changed as dictated by the processes being carried out at the target). As illustrated, the first temperature set point is 40° and is held until t₁, then the temperature is ramped to 80° over the time interval of t₁ to t′₁ and then held there until t₂, then the temperature is ramped down to 0° over the time interval of t₂ to t′₂ and then held there until t₃, and finally, the temperature is ramped to 40° over the interval of t₃ to t′₃ and held there. The phantom lines above and below the solid temperature profile line represent the fine temperature control.

FIG. 8 b is a graph of gate position as a function of time. The x-axis is time (t_(x), x=0, 1, 2, 3 . . . n, & t′_(x), x=0, 1, 2, 3 . . . n). The y-axis is gate position (the gate positions are for illustration only and may be changed as dictated by the processes being carried out at the target). FIG. 8 b illustrates how the gate positions may be changed to obtain the temperature profile shown in FIG. 8 a. Focusing only the time intervals where temperature ramping occurs, one will note that the during ramping (change in set point temperature) the gates may be opened wider to over shoot the desired temperature thereby shortening the time to obtain the next set point temperature (note the slight over shoot in the temperature profile in FIG. 8 a).

FIG. 8 c is chart illustrating how the controller 50 may be programmed to implement the gate position of FIG. 8 b to obtain the temperature profile of FIG. 8 a. As illustrated, two targets 14/14′ may be programmed into the controller 50. Each target 14/14′ may be operated independently so that different operations may be conducted simultaneously. The program for FIGS. 8 a-b is illustrated in the top line of the chart.

The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention. 

I claim:
 1. A temperature control system for a semiconductor manufacturing process having at least one target comprising: a heat exchange loop operatively associated with each target, and a mixing valve operatively associated with each heat exchange loop, said mixing valve having a body defining a mixing chamber, said mixing chamber having an inlet, an outlet, a hot inlet, a cold inlet, and a closure means associated with each inlet.
 2. The temperature control system of claim 1 further comprising two or more targets.
 3. The temperature control system of claim 2 further comprising a controller operatively connecting the target and said closure means.
 4. The temperature control system of claim 3 wherein said controller being adapted to control temperature at the target and/or time at temperature of the target.
 5. The temperature control system of claim 3 further comprising a temperature sensor at the target.
 6. The temperature control system of claim 3 further comprising an electronic circuit for operating the closure means.
 7. The temperature control system of claim 1 further comprising a source of hot heat exchange fluid at a predetermined hot temperature operatively connected to said hot inlet and a source of cold heat exchange fluid at a predetermined cold temperature operatively connected to the cold inlet, the hot temperature being different from the cold temperature.
 8. A mixing valve for a temperature control system for a semiconductor manufacturing process having at least one target comprising: a body defining a mixing chamber, the mixing chamber having an inlet, an outlet, a hot inlet, and a cold inlet, a moveable gate operatively associated with each inlet for controlling the flow of fluid through said inlets, and a motor for moving the gates.
 9. The mixing valve according to claim 8 wherein said motor being a stepper motor, a servomotor, and/or a hydraulic actuator.
 10. The mixing valve of claim 9 wherein said motor being a stepper motor.
 11. The mixing valve of claim 8 having more inlets for fluids at different temperatures.
 12. The mixing valve of claim 8 wherein said gate being associated with each said hot inlet and cold inlet.
 13. The mixing valve of claim 8 further comprising an arm connecting said motor and said gate.
 14. A process for manufacturing semiconductors by the step of: providing a temperature control system having at least one target including a mixing valve operatively associated with each target, the mixing valve having a body defining a mixing chamber, the mixing chamber having an inlet, an outlet, a hot inlet, a cold inlet, and a closure means associated with each inlet.
 15. The process of claim 14 wherein the temperature control system further comprises a heat exchange loop operatively associated with each target, and the mixing valve being included in the heat exchange loop.
 16. The process of claim 14 wherein the mixing valve further comprises a body defining a mixing chamber, the mixing chamber having a inlet, an outlet, a hot inlet, and a cold inlet, a moveable gate operatively associated with each inlet for controlling the flow of fluid through said inlets, and a motor for moving the gates.
 17. The process of claim 16 having more inlets for fluids at different temperatures.
 18. The process of claim 14 wherein said motor being a stepper motor, a servomotor, linear motor, and/or a hydraulic actuator.
 19. The process of claim 14 wherein the mixing valve further comprising a temperature sensor at the target.
 20. The process of claim 14 wherein the mixing valve further comprising an electronic circuit for operating the closure means. 